Selkirk Metalbestos 4RV-90 90 Adjustable Elbow, 4" Used when an offset is required to avoid obstructions such as rafters, joists and other construction obstacles. Used to orient pipe between vertical and horizontal orientation. Four piece adjustable elbow twists for easy offsets. Size refers to the inside diameter of the pipe or fitting. The outside diameter of RV is approximately 1/2" Larger. 3" Elbow - 3 Gore; 4", 5", and 6" Elbow - 4 Gore. Type B gas vent. Features Used when an offset is required to avoid obstructions such as rafters, joists and other construction obstacles Used to orient pipe between vertical and horizontal orientation Four piece adjustable elbow twists for easy offset Designed for use on approved gas appliances in residential and light industrial application Adjustable Stainless steel 90-Degree 6-3/8-Inch x 5-1/8-Inch USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.